content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.operators;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Predicate;
  import io.reactivex.rxjava3.internal.subscribers.DeferredScalarSubscriber;
  
  /**
   * Returns the first index of an element that matches a predicate or -1L if no elements match.
   *
   * @param <T> the upstream value type
   * @since 0.18.2
   */
  final class FlowableIndexOf<T> extends Flowable<Long>
  implements FlowableTransformer<T, Long> {
  
      final Flowable<T> source;
  
      final Predicate<? super T> predicate;
  
      FlowableIndexOf(Flowable<T> source, Predicate<? super T> predicate) {
          this.source = source;
          this.predicate = predicate;
      }
  
      @Override
      public Publisher<Long> apply(Flowable<T> upstream) {
          return new FlowableIndexOf<>(upstream, predicate);
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super Long> s) {
          source.subscribe(new IndexOfSubscriber<T>(s, predicate));
      }
  
      static final class IndexOfSubscriber<T> extends DeferredScalarSubscriber<T, Long> {
  
          private static final long serialVersionUID = 4809092721669178986L;
  
          final Predicate<? super T> predicate;
  
          long index;
          boolean found;
  
          IndexOfSubscriber(Subscriber<? super Long> downstream,
                  Predicate<? super T> predicate) {
              super(downstream);
              this.predicate = predicate;
          }
  
          @Override
          public void onNext(T t) {
              try {
                  long idx = index;
                  if (predicate.test(t)) {
                      found = true;
                      upstream.cancel();
                      complete(idx);
                      return;
                  }
                  index = idx + 1;
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  found = true;
                  upstream.cancel();
                  onError(ex);
                  return;
              }
          }
  
          @Override
          public void onComplete() {
              if (!found) {
                  complete(-1L);
              }
          }
      }
  }
  